This invention relates to a drive mechanism for a bicycle or other pedal driven cycle or exercise equipment. More particularly it relates to a vertical pedal drive for use with such equipment. It also is directed to a pedal drive mechanism in which the pedals move in the same plane, regardless if the plane is vertical or otherwise oriented.
Conventional bicycles are propelled by a pedal mechanism. The pedals are rotated by the operator applying a rotary force to the pedals in the same direction as the rear drive wheel. The pedals are opposed from each other. The pedals are fastened to a sprocket, which has a drive chain wrapped around it. The drive chain is also wrapped around at least one gear that drives the rear drive wheel of the bicycle.
This mechanism has been used for many years. The force applied to the pedals is a rotary force with the movement of the operator necessarily being a rotary movement. There is a dead spot where little or no power is applied to the sprocket. This occurs where the pedals are in the top and bottom positions. In this position the pedals must have a horizontal force applied to them to further rotate the pedals. A solution to eliminate the dead spot has been illustrated in U.S. Pat. No. 4,564,206 to Lenhardt. Lenhardt illustrates a modified pedal movement in which the circular pedal movement is modified by a closed loop path in which the pedals do not follow a circular path. The modified path eliminates the dead spot. However the short stroke provides a small force to the rear wheel during each stroke.
Another design that uses an up and down movement rather than a rotary movement is shown in U.S. Pat. No. 5,242,182 to Bezerra et al. Through a lever arrangement, power is applied to a gear mechanism, which in turn drives a chain and supplies power to the rear wheel. A problem with this system is that power from the operator is transmitted through a very short stroke resulting in a very small force applied to drive the bicycle during each stroke.
A pedal mechanism that allows the user of a bicycle or exercise equipment to use a stair climbing motion is illustrated in U.S. Pat. No. 5,662,346 to Toronto et al. This illustrates an attachment to a traditional bicycle drive in which the pedals provide a driving force to the rear wheel while the pedals are rotated in opposite directions. A reversing gear is added to the drive sprocket mechanism to provide a driving force to the chain drive. A shortcoming of this device, as in the other prior art devices, is that the drive mechanism still uses a substantially rotary movement of the pedals rather than a purely vertical movement.
In U.S. Pat. No. 3,939,719 issued to Stovall illustrates a bicycle that converts reciprocating motion to unidirectional rotation of an output shaft. The drive mechanism is attached near the bottom of the bicycle frame. The shaft driven by the reciprocating motion has one drive gear mounted on it, which in turn drives two clutches mounted driven gears.
It is an object of the present invention to provide a new and unique drive mechanism for a bicycle or other similar exercise device in which the drive mechanism uses a vertical up and down movement of the user""s legs. It is a related object to provide a pedal mechanism in which the pedals move in the same plane, which plane may be vertical, horizontal or in between the two. It is a related object to provide a drive mechanism that eliminates the rotary movement of the pedal drive mechanism of the past devices.
Yet another object is to provide a unique drive mechanism that provides power to the bicycle""s rear drive wheel during the downward stroke of either leg of the user. A related object is to provide power during the entire forward stroke while eliminating the loss of power due to horizontal movement of the pedals.
Still another object is the object of providing a new drive mechanism that uses the vertical stroke of the user""s legs, converts the vertical movement to a rotary drive, and provides the rotary power to the rear drive wheel of the bicycle. Related to this object is the object of providing power to the drive wheel by means of a unique reversing gear system that drives the rear drive wheel regardless of the pedal that is depressed.
Still another object is to provide a drive mechanism that uses a pair of gears mounted on one way clutches to provide power to the rear driving wheel.
An advantage of the unique drive system is that it transmits power to the rear drive wheel during the entire forward or downward stroke of either the left or right pedal. No power is lost as the pedals move only in the reciprocating direction.
These and other objects and advantages will be apparent from reading the Description of the Drawings and Description of the Preferred Embodiment.